1. Field of the Art
This invention relates to a machine for punching out assembled electronic circuitry parts from a carrier tape which carries a large number of assembled electronic circuitry parts or devices like TCP (Tape Carrier Packages) in a predetermined pitch along its length, a method for replacing carrier tape supply reels, and a method for producing assembled electronic circuitry parts or devices from a carrier tape.
2. Prior Art
In mounting an electronic parts or component on a circuit board, especially in mounting an electronic part like an IC (integrated circuit) device on a circuit board, it has been the general practice to mount an IC device directly on a wiring circuit board as in the case of so-called direct mounting system or to mount on a wiring board an IC device which has been assembled on a substrate film with a wiring pattern. In the latter case, electronic circuitry parts are assembled on a tape in a predetermined pitch in the longitudinal direction of the tape, and the electronic parts are punched out from the carrier tape one after another and mounted on a wiring board.
For instance, in mounting driver electronics parts on a glass substrate of a liquid crystal display panel, it has been widely known in the art to bond an ACF (Anisotropic Conductive Film) on lead portions of electrodes on the glass substrate of the liquid crystal display panel and then bond a substrate film of an electronic part on the ACF by application of heat and pressure. The ACF tape has conductive particles dispersed in a binder resin, so that, by application of heat and pressure, the binder resin is hardened to connect the wiring pattern on the substrate film electrically with the electrodes on the side of the glass substrate. This type of mounting is called, for example, TAB (Tape Automated Bonding) or COF (Chip On Film). A large number of electronic parts which are arrayed on a tape are cut or punched one after another from the tape immediately before they are mounted on a glass substrate, picking up and mounting each electronic part on the glass substrate by the use of a vacuum-operated handling means.
Therefore, the electronic parts punching machine is largely constituted by a tape feeding station, a tape punching station and a tape recovery or collecting station. Set in an operative position at the tape feeding station is a tape supply reel which is loaded with a roll of carrier tape having an electronic circuitry part carrier portion. Tape feed means are provided a tape travel route from the tape feeding station to the tape punching station and to the tape collecting station, and the carrier tape from the supply reel is fed pitch by pitch by the tape feed means to send the electronic parts carrier portions forward one after another. As soon as the tape is fed by one pitch, a punching means with a cutter unit is actuated to punch out and separate one electronic circuitry part from the tape. The punched electronic part is mounted on a glass substrate by means of a handling means.
Since there is a tape travel path of a certain length between the tape feeding station and the tape punching station, front and rear leader tapes of a length which at least corresponds to the length of that tape travel path are usually attached to the front and rear ends of an electronic parts carrier portion of the tape, respectively. The front and rear leader tapes contain no electronic parts. Accordingly, upon setting a tape supply reel at the tape feeding station, initially the front leader tape has to be fed forward as far as a position past the tape punching station, by an idle feed. In this connection, in a case where tape feed means are provided upstream and downstream sides of the tape punching station, the fore end of the front leader tape is drawn out at least to a position forward of the tape punching station in the tape feed direction and brought into engagement with the tape feed means. The supply of the carrier tape from the supply reel comes to an end when the last one of the electronic circuitry parts is punched out from the tape at the tape punching station. At the instant when the last electronic part is punched out, the rear end of the carrier tape is still supported on the supply reel by way of the rear leader tape which is connected to the rear end of the electronic part carrier portion of the tape.
In order to permit an interrupted punching operations at the tape punching station even after punching out the last electronic part on one tape, it has been the general practice to replace the tape supply reel currently used at the tape feeding station by a fresh tape supply reel, in the manner as follows.
In the first place, as soon as the last electronic circuitry part on the tape from the first supply reel is punched out at the tape punching station, the tape is fed forward until the tail end of its rear leader tape is displaced to a position forward of the tape punching station. Then, a fresh supply reel is set at the tape feeding station to replace the empty or consumed supply reel, and a front leader tape of the fresh reel is drawn out to a predetermined position along the tape travel path. In the next place, the fresh tape is fed forward to advance a foremost electronic circuitry part on the carrier portion of the tape to a punching position.
In this instance, the replacements of tape supply reels have thus far depended on manual labor of an operator although it is very troublesome and time consuming. In addition, while a consumed tape supply reel is being replace, despite great time losses, it has been necessitated to suspend an operation of mounting electronic circuitry parts on a glass substrate. Furthermore, the operator is required to pay careful attention to the progress of the tape punching operation in order to replace the supply reel in a best timing to avoid large time losses, i.e., to replace the supply reel as soon as the last electronic circuitry part of the currently operating supply reel is punched out at the tape punching station. This means that, in order to suppress the time loss to a minimum, the operator is required to stand by the machine well before the time point when the last electronic circuitry part advances to the punching station. The operational efficiency is deteriorated considerably by the reel replacements because the operator cannot do other jobs during each standby period.
Especially, as a result of recent progresses and improvements in automatic mounting apparatus for electronic circuitry parts, there has been a trend toward speeding up the tact time of electronic parts mounting operations, consuming the tape of each supply reel in a shortened period of time and as a result necessitating to replace the supply reel at a higher frequency. It is a paramount requisite to shorten the time period of the reel replacements in order to shorten the mounting electronic parts mounting time.